Long-Term Debt - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 16, 2025	Jun. 30, 2026	Sep. 30, 2026	Sep. 30, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Interest expense			$ 5,500,000	$ 17,500,000
Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Line of credit			0	0
Capital Account Notes | AT Umbrella LLC
Debt Instrument [Line Items]
Aggregate principal amount	$ 187,800,000
Capital Account Notes | AT Umbrella LLC | Minimum
Debt Instrument [Line Items]
Interest rate	6.31%
Debt instrument, term	2 years
Capital Account Notes | AT Umbrella LLC | Maximum
Debt Instrument [Line Items]
Interest rate	7.50%
Debt instrument, term	7 years
Capital Account Notes | Notes Payable | AT Umbrella LLC
Debt Instrument [Line Items]
Aggregate principal amount	$ 187,800,000
Capital Account Notes | Notes Payable | AT Umbrella LLC | Minimum
Debt Instrument [Line Items]
Debt instrument, amortization period	2 years
Interest rate	6.31%
Capital Account Notes | Notes Payable | AT Umbrella LLC | Maximum
Debt Instrument [Line Items]
Debt instrument, amortization period	7 years
Interest rate	7.50%
Holdover Note | AT Umbrella LLC
Debt Instrument [Line Items]
Aggregate principal amount	$ 162,300,000
Interest rate	7.63%
Debt instrument, term	8 years
Holdover Note | Notes Payable | AT Umbrella LLC
Debt Instrument [Line Items]
Aggregate principal amount	$ 162,300,000
Interest rate	7.63%
Post-service obligation payment period	7 years
Debt instrument, term	8 years
Revolving Credit Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Line of credit facility					$ 20,000,000.0
Cash borrowings					0
Revolving Credit Facility | New Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Line of credit facility		$ 50,000,000.0
Percent of accounts receivable, reduced by certain reserves		85.00%
Letter of Credit | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Line of credit facility			5,000,000.0	5,000,000.0
Standby Letters of Credit | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Outstanding amount			1,500,000	1,500,000	$ 1,300,000
Cash borrowings				$ 0
Floor interest rate (as percent)				1.75%
Participation fee (as percent)				1.75%
Fronting fee (as percent)				0.125%
Commitment fee (as percent)				0.25%
Commitment fee			$ 0	$ 0